1. Field of the Invention
The present invention concerns a foam spring in particular a foam spring with a tubular resilient body made of foam with holes extending inwards from the outside and which can be applied in the core of pillows, mattresses, armchair cushions or the like.
The invention also concerns a method of manufacturing such a foam spring.
2. Discussion of the Related Art
Such foam springs are known for example from US Published Patent Application No. 2005172468 and European Patent Document EP 0.872.198, disclosing a foam spring made out of a foam layer strip of for example latex or polyurethane foam, provided with slits, whereby the strip is bent and two opposite ends of the strip are glued together to form a hollow tubular body with diamond shaped holes formed by stretching the slits in a lateral direction due to the bending of the strip.
With the known foam springs the slits in the foam layer extend in a direction perpendicular to the foam layer strip, resulting in a foam spring with holes extending in a direction perpendicular to the outside surface of the spring at the position of the hole.
Said slits are made for example using straight knives with a cutting motion perpendicular to the surface of the strip.
Such springs can have a cylindrical shape with radially extending holes or rather a bi-conical shape as disclosed in US Published Patent Application No. 2005172468 or a barrel shape as disclosed in European Patent Document EP 0.872.198.